Whitemargin Unicornfish (Naso annulatus)

The whitemargin unicornfish (Naso annulatus) is a tropical fish found throughout the Indo-Pacific. It can reach a length of 100 cm making it one of the largest members of the family Acanthuridae.It is brown in color and has a distinguishing "nasal" protrusion. The tail is black surrounded by a white margin. It is often found in large schools off tropical reefs and feeds on zooplankton. The fish has two scutes on the left side. These are found on the caudal peduncle near the tail.

Source: http://en.wikipedia.org/wiki/Naso_annulatus